[PATCH v3 40/42] KVM: arm64: Allow sysreg ranges for FGT descriptors

[Ben Horgan]

Hi Marc,

On 4/26/25 13:28, Marc Zyngier wrote:
> Just like we allow sysreg ranges for Coarse Grained Trap descriptors,
> allow them for Fine Grain Traps as well.
> 
> This comes with a warning that not all ranges are suitable for this
> particular definition of ranges.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>   arch/arm64/kvm/emulate-nested.c | 120 +++++++++++---------------------
>   1 file changed, 39 insertions(+), 81 deletions(-)
> 
> diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
> index e2a843675da96..9c7ecfccbd6e9 100644
> --- a/arch/arm64/kvm/emulate-nested.c
> +++ b/arch/arm64/kvm/emulate-nested.c
> @@ -622,6 +622,11 @@ struct encoding_to_trap_config {
>   	const unsigned int		line;
>   };
>   
> +/*
> + * WARNING: using ranges is a treacherous endeavour, as sysregs that
> + * are part of an architectural range are not necessarily contiguous
> + * in the [Op0,Op1,CRn,CRm,Ops] space. Tread carefully.
> + */
>   #define SR_RANGE_TRAP(sr_start, sr_end, trap_id)			\
>   	{								\
>   		.encoding	= sr_start,				\
> @@ -1289,15 +1294,19 @@ enum fg_filter_id {
>   
>   #define FGT(g, b, p)		__FGT(g, b, p, __NO_FGF__)
>   
> -#define SR_FGF(sr, g, b, p, f)					\
> +/* Same warning applies: use carefully */
Nit: The other warning is a few hundred lines away. Consider identifying 
it more precisely.
> +#define SR_FGF_RANGE(sr, e, g, b, p, f)				\
>   	{							\
>   		.encoding	= sr,				\
> -		.end		= sr,				\
> +		.end		= e,				\
>   		.tc		= __FGT(g, b, p, f),		\
>   		.line = __LINE__,				\
>   	} 
Thanks,

Ben